feat(debug): -probes quits after measuring, so a ground check takes 14 s not minutes

The ground measurement was the slowest part of every iteration: the game ran until the shell's
timeout because nothing told it to stop. -probes now logs the top surface, the capsule and the
body's lowest point three seconds after spawn and quits on the next tick. A run went from minutes
to 13.7 s, which is the difference between one experiment per turn and one per five minutes.

Also applied set_complex_collision_as_simple to sidewalks and kerbs, as the terrain already had:
it did not make them block, so that flag is not their problem either.

And a correction that matters: the road is 366 and the sidewalk 380 in the shipped map. The 158 cm
I measured earlier came from the site blend's own Z datum, which sits about 2.2 m below the map's
because the terrain was added after that blend was written. So the float is about 14 cm - the
character stands on the road because the sidewalk does not collide - not the metre it looks like
against the kerb.

Game/GigLine/Source/GigLine/GigLineCharacter.h

@@ -210,6 +210,9 @@ protected:
 	UPROPERTY()
 	TObjectPtr<class AStaticMeshActor> CameraTestWall;
 
+	/** `-probes`: log the ground measurements, then quit. */
+	bool bProbeAndQuit = false;
+
 	/** Seconds until the foot-contact probe runs; 0 disables it. */
 	float FootProbeDelay = 0.f;
 	void LogFootProbes();